Historically, the HSF was not in the early Service Manual. I think it first appeared in a bulletin about certain transmission DTCs. That bulletin was later updated to reflect the fact that the service manuals were updated to include the necessary information. And, at some point it was added as step one of the DCT filter change procedure. Then later it was further clarified in the Service Manual with additional instructions about what to do if the filter change is beyond the service interval.

So it became both a potential remedy for certain transmission issues (and forum reports indicate that it sometimes solved a problem), and it became a step in a routine maintenance procedure.

Josh Holder said if you are a DIYer, you don't have to do it.

Josh's statement makes it sound like its not important. But then why does the procedure not only include it, but also include additional instructions about changing the filter first if its beyond the service interval, then doing the HSF, then changing the filter again after the HSF? If its really unimportant, why not just skip it? Why was all that written into the procedure.

And, if running down the road does the same thing, then why does the HSF sometimes resolve a transmission issue that was not already resolved by running down the road (as reported several times on the forum). And since its been established in several threads that the HSF software does not even reside in the earlier model year cars (which is why some aftermarket scan tools can't run it), how can they be running that routine driving down the road?

It seems like it was important enough that GM added it to the procedure, and also chose to add the HSF software to the later model cars.

 

Whether or not performing the hydraulic system flush is a requirement when doing a DCT filter change boils down to if you believe it is a requirement to perform service procedures to the service manual; and if verbal comments by a Corvette team member can supercede documented requirements.

 

so true! Changing the DCT filter and engine oil is easy enough as a DIY task...

 

How can Chevrolet FORCE you to do maintenance at their dealership? My understanding is that even for warranty purposes they cannot.

 

They can't and don't force owners to have work done at a dealer, and that is clear in the warranty manual. But they can deny a warranty claim for damage caused by improper maintenance. Again in the warranty manual.

"Damage caused by failure to follow the recommended maintenance schedule intervals and/or failure to use or maintain proper fluids, lubricants, or refrigerants between maintenance intervals recommended in the Owner's Manual is not covered. "

The Owner's Manual indicates a that the DCT external canister filter must be changed at certain mileage intervals (and also every 24 hours of track use). And there is a procedure for that in the Service Manual, which includes the HSF as step one. So, is it a requirement to perform the documented procedure correctly, or can a verbal statement from a GM rep supersede the documented procedure?

The GM tool is available to the public at a cost (as any tool is) and there are also aftermarket tools that will perform that procedure now as well, so no one is forced to go to a dealer to follow the procedure. You are "forced" to obtain a tool if you want to follow the procedure.

There have been no report of the denial of a warranty claim due to not performing the HSF. But do you really want to skip it, warranty or not? Its purpose, as stated in the documented procedures is to actuate the solenoids in a specific manner to flush debris from the system. As noted, it has been reported to sometimes resolve transmission issues that were not resolved by simply driving down the highway. Given that Josh said DIYers dont't have to do it, I think its a personal choice. But I want it done when my filter is changed.

 

They're not forcing you to do the maintenance at the dealership. It be can be done by an independent shop or DIY. But you do need evidence that the service was done properly for warranty purposes.

 

Can't see where you are required, as an owner, to purchase said service manual. If it was a requirement to have, then GM should have to supply it. If you don't have it, you can't follow it.

 

You don't have to purchase their service manual but you are still required to perform the procedure correctly however you get the information. This is true of any car warranty. Cars are complicated these days and things like torque values, etc. can be critical. There are other sources of the repair procedures besides GM. ALDATA offers a 1 month subscription and a 5 day free trial.

 

And that was your original point - it depends on whether its a requirement of not. I personally think performing most maintenance on this car without the Service Manual is fraught with peril, whether its required or not. There are stories on the forum about twisting off bolts due to improper torque, brakes activating during a brake job because of failure to understand the procedure or even how the brake system works. Plenty of example I think, of why DIYers should obtain the relevant service procedures - free or not - and warranty or not.

But per the Warranty Manual (that I quote from time to time) you don't necessarily have to perform any maintenance, or keep any records. It says this: "GM cannot deny warranty coverage
solely for the lack of receipts or for your failure to ensure the performance of all scheduled maintenance." But it also says, very clearly, that damage caused by improper maintenance will not be covered. So, a slight variation on the point - it depends on whether or not failure to perform the HSF is "improper maintenance" and furthermore, whether or not failure to perform the HSF could result in damage. And, if avoiding damage is not sufficient motivation (irrespective of the warranty issue) - I suppose one could add it depends on whether GM will deny coverage, should the damage happen after a failure to include the HSF when the filter was changed. But avoiding a transmission issue in the first place would be sufficient for me.

I want it done because its a step in the procedure and I think it is a preemptive action to avoid buildup of debris in the hydraulic system (valves and lines) which, if not done, might result in a failure later. The procedure is described in the Service Manual as actuating the solenoids in a specific manner to flush debris from the system. I further do not believe that driving down the highway accomplishes the same thing because the HSF software does not even reside in the earlier models (2020-2022 I think), and because the HSF has resolved problems that were not resolved by normal driving. For me, this is sufficient evidence that debris can, for whatever reason, accumulate in the hydraulic system and that the HSF can be effective in removing it. So, yes, I believe it is possible that "damage" could result later if it is not done. I'm not even citing a potential denial of warranty coverage as my reason - and I do not know if GM would deny a warranty claim and cite failure to do the HSF as the cause.

Others are free to believe differently.

 

When I do any work on mine, I get a 3 day subscription $22 for service manual access.

 

"I want it done because its a step in the procedure and I think it is a preemptive action to avoid buildup of debris in the hydraulic system (valves and lines) which, if not done, might result in a failure later" Could not have said that better, I do all my own work. And I have the procedure done, by a third party. This may be the catch can mod for your DCT.